The present invention relates to a belt-type drop former apparatus for producing granules from a freeflowing viscous mass. The mass is reduced to the form of drops that fall onto a cooling surface where they solidify and gel. Such an apparatus conventionally comprises a supply vessel to which the freeflowing mass is supplied, the vessel having outlet openings which are intermittently opened and closed by the lower run of an endless perforated belt guided on front and rear guide drums. That lower run travels from the front guide drum to the rear guide drum and passes across the outlet openings of the supply vessel. When openings of the belt are aligned with the outlet openings of the supply vessel, the mass falls therethrough to form the drops. A collecting device is arranged for collecting the residual material which does not fall from the belt. Rather, the residual material is discharged from the openings of the belt as the belt travels around the circumference of a rear guide drum. The collecting device embraces at least part of the outer circumference of both the guide drum and the belt, and conducts the collected material to a collecting channel intended for delivering the collected residual material onto the perforated belt upstream of the supply vessel.
A belt-type drop former of this kind has been known from U.S. Pat. No. 5,591,458 wherein collecting walls are provided inside the endless perforated belt. The collecting walls converge downwardly in V shape from the two guide drums to a collecting channel arranged upstream of the supply vessel (i.e., the vessel having the outlet openings for the material to be dropped, which material is supplied to it from the side). It has been found that such collecting walls are not absolutely necessary, being capable only of returning the material that drops down from the upper run because the largest part of the residual material that has not already been discharged through the openings of the belt during the dropping process as such has been previously discharged at the first guide drum. The latter, being arranged downstream of the supply vessel, viewed in the running direction of the lower run of the perforated belt, is however likewise provided with a collecting means. Notwithstanding the schematic depiction in U.S. Pat. No. 5,591,458 of a conduit extending from that collecting means to a collecting channel located upstream of the supply vessel, the task of returning residual material through such a channel is not easily performed.
The present intention, therefore, has for its object to design an apparatus of the before-mentioned kind in such a way that the residual material collected by the collecting means at the first guide drum, i.e. the rear drum viewed in the running direction of the belt, can be returned easily, but in a safe way, to the collecting channel arranged upstream of the supply vessel.